Pneumatic interlocking device for preventing improper closing of a circuit breaker



Patented Dec. 12, 1950 PNEUMATIC INTERLOCKING DEVICE FOR PREVENTING IMPROPER CLOSING OF A CIRCUIT BREAKER John F. Chipman, South Weymouth, Mass., assignor to Allis-Chalmers Manufacturing `Cornpany, Milwaukee, Wis., a corporation of Dela- Ware Application January 18, 1949, Serial No. 71,506

(Cl. 20D-82) 14 Claims. 1

This invention relates in general to switching devices Such as electric circuit breakers of the uid blast type and more particularly to pneumatic control systems therefor.

Heretofore, improper closing operations of circuit breakers have sometimes occurred when a tripping impulse was immediately preceded by a closing impulse. Such faulty operations may. have been due to limited effectiveness of dumping or exhaust valves.- Pneumatic motors are normally provided with valves for dumping compressed air from the closing side of the cylinder and the pipe system associated with it when a tripping impulse is being given. If the dumping valve of a pneumatic contact operating motor is not sufiiciently eifective, there may remain a considerable residue oi air under pressure in the portions ofi the pneumatic system that are associated with the closing side of the cylinder. That residue of air under pressure may not' be capable of accomplishing a normal closing operation, yet it may be sufficient to effect a slow and limited reverse movement of one of a pair of separated contacts, resulting' in a decrease of the amount of contact separationbelow. the requisite safe minimum distance. Such a decrease will be followed by a breakdown of the gap between the contacts. Abreakdown occurring across a reduced gap between a pair of disconnect contacts of an airy blast circuit breaker, thearcing contacts of which have been locked out by pressure responsive lockout means on account of a temporary reduction of pressure inthe blast reservoir, may be of most serious consequences.

Circuit breakers have been provided with trip predominance lockout valves which operated by trip or blast air and in so doing lock or close the conduit supplying fiuid under pressure for closing thel circuit breaker; pulse and a closing impulse are given substantially'simultaneously, the trip impulse predominates since it results in locking the closing air conduit, thusprecluding the occurrence of a closingk operation. It' is not sufiicient, however, to provideY a single trip predominance lockout valve, because, in case of contradictory operating impulses, improper closing might occur upon removal of the trip impulse if the closing impulse still prevails;

Bt is, therefore, one object of the present invention to provide a new and improved pneu.- matic control system for circuit breakers of the iiuid blast type.

Another object of the invention is to provide a When a trip imnew and improved pneumatic operated control system which precludes closing of the circuit breaker if closing and tripping impulses are being given substantially simultaneously.

Still another object of the invention is to provide a new and improved pneumatic circuit breaker control system which precludes closing of the circuit breaker following a tripping operation if closing and tripping impulses are being given substantially simultaneously, but which permits closing of the breaker upon removal of the original faulty closing impulse and upon an additional closing impulse being given which is not accompanied by a simultaneous tripping impulse.

A further object of the invention is to provide 'a new and improved pneumatic circuit breaker control system in which the fluid under pressure provided for closing the circuit breaker asssts the fluid under pressure provided for tripping the circuit breaker to lock out the circuit breaker closing means when closing and tripping impulses are simultaneously received.

A still further object of the invention is to provide a new and improved dual purpose circuit breaker control system which precludes closing of the circuit breaker following a tripping operation if closing and tripping impulses are given substantially simultaneously and also precludes closing of the circuit breaker if the breaker is in the process of being removed from its cell wherein it is normally housed.

A still further object of the present invention is to provide a pneumatic'circuit breaker control system in which the action of the pressure of closing air upon the movable valve element of a lockout valve is balanced during normal closing Yoperation of the circuit breaker.

A still further object of the present invention is to provide a pneumatic circuit breaker operating system in which the action of the dumpingvalve for the closing conduit of the pneumatic motor is supplemented by Venting the pneumatic system at a point remote from the dumping valve.

A still further object of the present invention is to provide a pneumatic circuit breaker operating system in which portions of the system that are associated with the closing side of the cylinder of a pneumatic Contact operating motor may be Vented by a lockout valve controlling the supply of closing air.

Objects and advantages other than those set forth will be apparent from the following description when read in connection with the accompanying drawing in which the single figure assumed herein to` be compressed air, supplied from a suitable compressor (not shown). Although in general, circuit breakers of the type herein considered are provided with a plurality of similar pole structures, one for each phase of a polyphase electric circuit, only one such pole structure or pole unit is shown in the figure and the circuit breaker will be described in detail as if it were of the single pole type.

The circuit breaker, for example, may comprise a Xed arcing Contact 3 and a cooperating movable arcing contact i connected in series with a disconnecting switch comprising a fixed disconnect Contact 5 and a cooperating movable disconnect contact ii in an electric circuit through stud terminals l and t. rl'he arcing contacts 3 and #i are housed in a tubular arcing chamber il, having a metallic sleeve shaped wall iii axially aligned ywith and supporting an insulating sleeve il and an insulating sleeve i2. The metallic sleeve Vlll of chamber 9 constitutes a conductive connection betvz een the fixed arcing contact 3 and an extension of terminal 3. Sleeve H constitutes a discharge passage for chamber Q.

Sleeve l!) is provided with an inwardly extending bracket It upon which is arranged a contact constituting the iixed arcing contact :l oi the circuit breaker. The cooperating movable arcing contact il, which may be in the form of a streamlinedY solid of revolution, is actuated by a fiuid motor I3 comprising a piston slidable in insulating sleeve I2 and secured to a stud l5. The piston of fluid motor l5 comprises a metallic sleeve member 28, an insulating hub 2i secured to member 2d at the upper end thereof, and a hub il secured to member 2S and stud i6 at the lower encl thereof. Arcing contact 4 is suitably secured to a stud 2B which is slidably mounted in insulating hub 2i and biased to closed position by a spring 22 acting between a bushing 23 secured to stud 2@ and an extension 2d ci hub il. The stud 2i! is conductively connected to the stud i8 by means ci flexible conductors 25.

A pair of main or current carrying contacts 26 and 2l are in parallel with the arcing contacts 3 and ii. Contact 2e is preferably made Vin a series of segments resiliently mounted to form an annular stationary contact. The movable current Vcarrying contact 2l' is diagrammatically represented as a part ci metallic sleeve member 28 which is secured to insulating hub 2i and hub il so as to move with the piston upon actuation Vurged into engagement with the iixed current carrying contact 2S by resilient means such as a spring 29 acting between hub Il and a metallic washer 3e which is resiliently supported in a metallic sleeve portion 3i. The metallic sleeve portion 3i is supported by insulating sleeve i2 at the free end thereof. Sleeve portion 3l is axially aligned with sleeves i9, H and i2. In addition sleeve portion 3l. is provided with an extension arm 32 whichsupports the xed disconnect contacts 5f The insulating sleeve portion l! communicates with a cooling chamber 331 The sleeve portion H may contain an auxiliary arcing electrode 34 which is usually affixed thereto and coaxially Valigned therewith. The auxiliary arcing electrode 3e is connected in series relationship with the disconnect contacts 5 and li and a current limiting resistor 35 by means of conductor l5.

rThe movable disconnect contact S may be pivotally mounted on a bracket 35 which is secured to an extension of terminal l. One end of a connecting rod 3l may be connected at a point 38 intermediate'the ends of movable disconnect contact 5, andthe other end of rod 3l may be connectecl-to an arm 39 of a bell crank 40. A' second arm il! of bell crank il may be connected to the.

piston rod 42 of a Viuid motor 45. The rod 42 protrudes through and beyond the ends of a cylinc-.er 44 or" motor 45. Motor 45 actuates the bell crankv 4@ which, in turn, actuates the connecting rod 42. A predetermined movement of connecting rod 3l actuates the movable disconnect con-V tact C5 and moves it to its open and closed positions. A pair of regulating valves c6 and 41 may be utilized for regulating the supply of iiuid from reservoir 2 to motor d5.

A mechanical interlocking device precludes improper sequence of operation oi the disconnect contacts and t with reference to the arcing contacts 3 and 4. The mechanical interlocking device comprises a means such as an abutment or bent lever 43 which is pivotally mounted at 5l on a bracket 49 and is arranged to lie withinthe path of movement of rod or stud IS which is actuated with arcing contact 4. Lever 4B also lies in the path oi movement of the disconnect contact 6 for preventing separation of the disconnect contacts 5 and 5 prior to .opening of arcing contacts 3 and 4. A biasing means, such as a spring 5G, pivots the lever 48 into Vthe path of movement of the movable disconnect contact 6 and precludes separation thereof from thestationary or fixed disconnect contact 5 prior to separation of arcing contacts 3 and 4 which Iwould ing contacts 3, 4 are fully separated, the discon- The air under pressure in reservoir 2 :also proiducesathe arc extinguishing blast across the gap'. formed. between. the pair of;y cooperating arcing. contacts, 3 ,I 41 uponY separation thereof. The arc extinguishing.blastirorn reservoirf'Z 'to'. the' arcing. contacts'A 3; 4' is controlled' by' a.' blast valve 52. which provides'. aconnection between the reservoir Zand an insulated conduit 53'which.=is connected to the metallic` sleeve por'- tion 1010i' chamber 91'.

Differentialf type blast valve 52i employing aY pilot' valve therefor' comprises' fluid motors 54 andl'55 forcontrolling a blast inlet ports'. Motor 541 comprises a. cylinder 51; a: piston. 5.3, a spring: 59, and an inletrportri. Motorscom.- prises a cylinder 6l; a pistonG-Z, a: return-.spring 63, for pistonl 62, an exhaustportri. Valvet for closing-exhaustfport SSiis adaptedlto vbeloperated' by motor 55; A. cylinder 611 surrounds cylinder Si ofiinotor 55`coaxiallytherewith.Y Cylinder 61 is provided' with an. exliaust'portv 63. Piston 62, when actuated by'airunder pressure,l actuates valve 65 and opens exhaust port 3.5 against the action of spring' 63. As long as exhaust.V port 65 remainsl closed, air under. pressure supplied iromfreservoir 2 through inlet port 60 cooperates' withspring G3 to'A maintain the valve 65 in the position shown.

Inletport 11 of blast valve 52- supplies `iiuid-motor 55" with operating' fluid under pressure for actuating'piston 622 Inlet port 1I', however, is controlled-by aslide valve 12 whichopens and closes port 1i upon a predetermined movement-'of piston43 of fluid motor 45. Connecting rods 13 and 14, interconnected by link 15v and oi'whicl'i the former is connected-to slide valve 2by'ineans of link-1E, form a mechanical connection between rod l2v ofl piston i3-to slide valve-12; The move-- mentof slide'valve 12 also opensandcl'osesan exhaust port' 11 for dumping fluid under pressure from the right side'of-'piston 62-"of iiuidimotor 55.

A pairof opening-andclosingnieans'such as solenoid type controlv valves 18 an'd'19, respectively, controlthe actuating means' for theV circuit breaker. Both control valves 18 and19`are connected to reservoir 2`by a, common conduit to.

InV accordance with the present invention a: means which, for example; may be a slide or piston type interlocking valve 53 is providedand arranged in'a conduit 8B; l813 for connecting the closing valve-19` andtheY iiuid operated motor''". Valvetl comprises acylindrical'valve housing 85 dening a-passage inter-connecting conduit 'por-v tions 86; 84', a valve element' 8b', and biasingmeans such as a spring 9D acting upon valve ele-i mentitol in' a direction'longitudinally thereof and tending'tomaintain valveelement 85 inits=open= position. Elementi' 86- is adapted to'I be moved selectively to the'fopen position shown andftoa closed'ipositionandmay comprise axially aligned pistons'l 81" and 88 which are'slidable into valve' housing 85 and' arefjoined by'astem portion' il. Fluidunderpressure is enabledlto iiow through valve housing d5' when valveeleinent 851s inopen position'.

Valve-housing 85v denes' means such'as a-iirstV port S3- for admitting' therein Huid under-pressure from aI conduit' 9111' which is connected` to conduit 53. Valve housing'S-, inladdition, com'- prisesmeans suchl as a.I secondi port 9E: for. admitting' fluid under presslu'e" from. conduit sec.- tion. 8d', means defining aithirdport-Q' fon-interconnecting housing.' 85` and motor means` it; and' means defining, a.- fourthport 9BV and: fifth port'v 98".. Port $18r serves Athepurpose. ot. exhaust- 'the action of spring 63.

ing. residual airtrapped in cylinder M on the rightJside of piston 43 and in conduit. 84, while port 98 serves. the purpose of venting compressed ainthat 'may leak between the pistons B1, 88 and the walls of' valve 83 to the lower end of valve housing.` 85. Int its open position shown, piston 81 is situated between the first port 93 andthe secondfport When valve element 85 is in itsclosed position, piston 31 is situated between the second port Stand the third port 9.1.

Port 91 is always situated between pistons 81 and 88.`

The piston type interlocking valve 83 may be mechanically operated'to lockout position ifv the circuitbreaker is removedfrom its cell 99. Rod i90, which may press on piston 81 of valve element 86, is actuated in an upward directionwhen the circuit breaker, which forms part of a' vertical lift arrangement, is in position in cell 9%. This actuationA off rod |09, upward, frees valve element 86' and permits it'to assume its open position. Rod |09 is actuated upward when the circuit breaker is raised intoposition in celle!) by abutment of a connecting' rod m3 against' a structural member 164-. The abutment of' rod i133 against member IM results in rotation of a linkio5in a counterclockwise direction and thus applies tension to a helical spring i355 Lower'- in'g of the circuit breaker to permit removal thereof 'from cellg permits'spring $95 to contract; Springl H16 is stronger'than spring Sil-located'within valve -83 and hence when the breakeris lowered'irom its cell 529,1 spring it@ aetuates valve element 8B toitsclosed position.

The circuit breaker illustrated in the drawing is shown with the disconnect contacts in the opencircuit position and the pneumatic control system in the corresponding position. A closing operation is initiatedby energization of the closing solenoid'valve 19, thereby causing air under pressure from reservoir 2 to pass through conduit 8G, valve19,` conduit 84', valve 83, conduit 84 to fluid' motor 45. Operation of solenoid valve 19 results in piston 43 of motor 45' moving from right't'o left to actuate rod d'2, bell crank 110, and connecting rod 31, thus closing the disconnect contacts Sand G. The movementI of piston 43 of motor 45 from right' to left'rotates link 15 clockwise, and this results in an upward movement of connecting rodv 14 which in turn rotates link 16 in a clockwise direction. The clockwise rotation of link 16 actuates slide valve 12in an upward-direction, thus opening port 'il and closing exhaust ports 11.

The passage' of air through ports 9E and 91 of valve 83 during av closing operation of the circuit breaker does not actuate valve element 86, because the pressures applied thereby to pistons 81 and' 38 are equal.

When' the solenoid' trip' valve 18 is energized, compressed air flows from reservoir 2, through conduit 8U, trip valve 18, a conduit |91, and inlet port" 1'I` of slide'valve 12. This causes air from reservoir'Z toy move piston 62v of motor 55 against The movement of pistonZ under the action of air pressure from reservoir 2 moves valvev 65 and opensport 65 in cylinder B1. Uponopening of port 66, air under pressure trapped in cylinder 61 exhausts to the atmosphere through port 53. This exhausting action reducesthe pressured behind piston 58=oimotor 54 andenables the'airunder pressure inireservoir- 2y acting on the portion ofthe left sideofpiston 58 surrounding the seat of the'blast'valve to overcome the action of spring A blast of air under pressure then flows through cylinder 51 of motor 514 left of piston 58, inlet port 56, conduit 53, and an inlet port ||i in sleeve portion Il) of chamber 9. Air under pressure in chamber 9 acting Von insulating hub 2| actuates the piston of motor I8 andthe piston Ysequentially opens the current carrying contacts 28 and 21 and the, arcing contacts 3 and Insulating hub 2|, being secured to sleeve member 28, moves sleeve member 28, hub |1,`and stud I in contact opening direction, thereby separating first the current carrying contacts 26 and 21 and shortly thereafter (upon the engagement of hub 2| and bushing 23) the arcing contacts 3 and 4. The air blast extinguishes the arc that occurs upon separation of the arcing contacts 3 and il.V

Upon a predetermined travel of stud I5, which is actuated by the piston of motor I8, a portion thereof abuts against lever 68. The movement of lever d3 moves one arm thereof out of the path of movement of the movable Ydisconnect Contact 6. The proper sequence is assured by interlock lever d8 but timing is governed by rate of flow of air controlled by valve 46.

Upon the flow of the air blast through conduit 53, air under pressure therefrom is transmitted through a conduit |88 connected thereto and to anY inlet port |98 in motor 45. This pressure impulse moves piston d3 of motor 45 from left to rightthus resulting in the separation of the disconnect contacts 5 and 6. If the desired predetermined sequence of operation of fluid motor I8 resulting in separation of the arcing contacts 3 and 4, and of fluid motor i5 resulting in separation of the disconnect contacts 5 and 6, does not occur, the lever 48 will prevent disconnect contacts 5 and 5 from separating as long as arcing contacts 3, are Y not fully separated. However, if uid motors I8 and 65 operate in the proper sequence, lever 48 will be moved out of the path of movement of disconnect contact 5 Without physical engagement thereof before fluid motor 45 actuates disconnect contact 5. Y

Upon the flow of an air blast through conduit 53, air under pressure therefrom is transmitted through conduit 84, through inlet port 93, to valve 83. This pressure impulse moves valve element SB'into the closed position thereof against the action of spring 89. Such Vmovement of valve element 86 brings piston S1 below port'SE, whereby the connection between port Q6 and port 91 is interrupted. The closing of the connection precludes the possibility of air under pressure being supplied through port 91 to motor 45, which might result in closing the disconnect contacts prematurely. Y Y

. Opening of disconnect contacts 5, 6 `effects resetting of blast valve 52 by cutting off of air feed through port 1| by positioning of slide valve 'l2 and simultaneous venting of the actuating air from chamber of piston 52 through port 11.

last valve 52 closes and stops the flow of uid through conduit 53 and adjacent the arcing contacts 3 and. The action of springs22 Vand 29 then closes the arcing contacts?, and and the main current carrying contacts 26, 21. The re'- duction of pressure in conduit St enables spring 90 to returnvalve element 85 to its open position. Y

If opening and closingimpulses are substan tially simultaneously initiated by valves "illY and 19, respectively, air under pressure from conduit 53 againV moves valve element- 86, against the action offspring 86. This prevents the closing" impulse from owing through valve 19, valve 83, conduit 84 to fluid motor 45. Disconnect contacts 5 and' cannot be closed during the period of time a tripping impulse prevails. 'Ihe lockout feature of valve 83 is aided by the action of the closing impulse which ows through valve. 'i8 and port 96 into the space in valve 83, above piston 81. This closing impulse thus aids the blast air from conduit 53 in locking valve 83 in its closed position. Once actuated to closed position, no closing impulse can be passed through valve 83 as long as either closing valve 19 or blast valve 53 remain open since either or both will feed air to chamber above piston 81, thereby holding valve 83 in closed position. In the lockout position of valve element 36, ports 91 and 93 are in communication, resulting in venting of the conduit 84 which Yconnectsvalve B3 and iiuid motorE. Port 98' is provided to vent air which might leak by piston 8B, thereby preventing resetting of valve 83 due to lbuild-up of pressure behind piston 88.

In the lockout position of valve element 88 fluid under pressure from conduit ell maintains valve element in its lockout position even though admission of fluid under pressure through port 93 has ceased. f

While the embodiment shows how the present invention may be applied to a circuit vbreaker having separate arcing contacts and disconnect contacts, it will be apparent that the invention is not limited to Vcircuit breakers of this Y Yparticular type. VIt is equally applicable to circuit breakers Which have but one single set of contacts serving 'the purpose of forming anV arc gap for initial circuit interruption as well as the purpose of increasing the amount `of circuit insulation upon interruption of the circuit at that arc gap. It is also apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent: g

1. In a switching arrangement, the combination of a switching means for opening and closing an electric circuit, pressure operated means for actuating said switching means, a source of fluid under pressure, a conduit for supp-lying fluid under pressure from said source to said pressure operated means, a first valve for controlling the admission of VVfluid under pressure Vfrom said source to said conduit, a second valve arranged in said conduit between said'rst valve and said pressure operated means, means Vfor biasing said second valve to the open position thereof, means for initiating closing of said second valve, closing means distinct from said initiating means and operative upon operation of said initiating means for maintaining said second valve lclosed, said closing means being actuated by the fluid undery pressure in the section of said conduit situated between said first and second valves formamtaining said second valve in the closed position thereof, said Second valve preventing uid under pressure from said conduit from acting upon said closing 4means of said second valve prior to operation of said initiating means.

2. In a switching arrangement, the combination of relatively movable contact lmeans for opening and lclosing acircuit, a motor operated by uid under'pressu're for actuating vsaid contact means, a source of uid under pressure, a

1 conduit for supplying fluid under pressure from said source to said 'iiuid operated motor, -a'first `valve for controlling the admission of fluid under pressure from said source to'said conduit, a second valve arrangedin said nconduitbetween said 'rst valve and rsaid fluid operatedmotor, resilient means for biasing said second valve to the open position thereof, motor means for closing said second valve against the action of said resilient means, means connecting said motor means with said sounce to cause closure of said second valve, and means responsive to operation of said motor means for connecting said motor means with Athe section of said conduit situated between said first and second valves yfor maintaining rsaidsecond valvein closed lposition thereof.

3. In a switching arrangement, the combination of a pair of relatively movable contacts for opening and closing acircuit, a contact operating'motor to be operated by uid under pressure for relatively moving said pair of contacts, a

source of `fluid under pressure, a conduit for supplying fluid under pressure from said source to said contact operating Ymotor for closing said pai-rof contacts, a first valve for controlling the Vpassage of fluid under pressure from said source 'to said conduit, a second valve arranged in said said rst valve and said second valve to said valve closing motor, said last mentioned means including means for causing admission of fluid under pressure to said valve closing motor upon closing vof said second valve and for preventing the admission of fluid under pressure to said valve closingimotor prior to closing of said second valve.

4. In a switching arrangement, the combination of a pair of cooperating contacts for opening and :closing an electric circuit, fluid operated motor means-for actuating said contacts, tripping means forfcausing actuation of said motor means to separate said contacts, a first conduit supplied with fluid under pressure upon operation of said tripping means, a closing valve, a second conduit controlled 'by said closing valve to supply fluid under pressure to said motor means for closing said contacts, an interlocking valve arranged in said second conduit, resilient means for biasing said interlocking valve to the open position-thereof, motor means of the cylinder p-iston type for closing said interlocking valve, said motor means being supplied with fluid under pressure from said V.first conduit, means providing for the admission of uid under pressure from said second conduit to said motor means upon closing of said interlocking valve, and means under the control of -said interlocking valve for preventing the admission of fluid under pressure yfrom said second conduit :to said motor means as long as said interlocking valve remains -in the open position thereof.

5.In a switching arrangement, the combination of a pair of cooperating contacts for opening and closing an electric circuit, fluid operated motor means for actuating saidcontacts, tripping Ymeans forcausing actuation of said motor means'to separate said contacts, a rst conduit `supplied With fluid under pressure upon operation of said tripping means, a closing valve, a second conduit controlled by said closing valve to supply liuid under pressure to said motor means for closing said contact means, an interlocking valve arranged in said second conduit and `comprising a balanced valve element tc be moved selectively to an open position and tc a closed position, spring meansfor biasing said valve clement tothe open position thereof, a reciprocatory fluid operated-motor comprising a piston connected to said-first conduit for moving said valve element tothe closed position thereof, means deninga port for admitting uid under pressure from said irst conduit to said reciprocatory motor means in valve closing direction, means for preventing fluid under pressure in said second conduit from actuating saidreciprocatory motor in eithervalve opening direction or valve closing direction, and means operative upon movement of said valve element to the closed position thereof for r rendering said preventing means in- 'eifective'and for causing fluid under pressure in said second 'conduit to act upon said piston of the reciprocatory ymotor in valve closing direction.

6. In a switching arrangement, the combination of a plurality of cooperating arcing contacts in series with a plurality of cooperating disconnect contacts, a first motor means actuated by uid under pressure for separating said arcing contacts, a sccond'motor means actuated by fluid under pressure for disengaging said disconnect contacts, a source of fluid under pressure, tripping meansfor initiating separation of said arc- Ving `contacts and of said'disconnect contacts by said 'rst and second motor means respectively and for initiating establishment of an arc extinguishing blast of fluid under pressure from said source adjacent said arcing contacts, a first conduit supplied with uid under'pressure upon operation of said tripping means, a closing valve, a .second conduit controlled by said closing valve for supplyingiuid underpressure from said source to said second motor means for closing said disconnect contacts, an interlocking valve arranged in said Second conduit and comprising a balanced valve element to be moved selectively to an open position and to a closed position, spring means for biasing Vsaid valve clement to the open position thereof, a fluid operated reciprocatory inotcr for moving said valve element to the closed position thereonmeans defining a port for admitting fluid under pressure from said first conduit to said reciprocatory motor in valve closing direction, means for preventing uid under pressure in said second conduit from acting upon said reciprocatory motor in either valve opening direction or valve closing direction, and means operative upon moving of said valve element to the closed position thereof for rendering said preventingmeans ineffective and for causing fluid under pressurein said second conduit to act upon said reciprocatory motor in valve closing direction.

7. In'a switching arrangement, the combination of a plurality of cooperating arcing contacts in series with a plurality of cooperating disconnect contacts, a rst motor means actuated by fluid under pressure for separating said arcing contacts, a second motor means actuated by fluid under pressure for disengagng said disconnect contacts, a source of uid under pressure, tripping means for initiating separation of said arcing contacts and of said disconnect contacts by said 'il first and second motor means respectively and for initiating establishment of an arc extinguishing blast of nuid under pressure from said source adjacent said arcing contacts, a valve, a conduit controlled by said valve for supplying fluid under pressure from said source to said second motor means for closing said disconnect contacts, an interlocking valve arranged in said conduit, means for biasing said interlocking valve to the open position thereof, a fluid operated reciprocatory motor for closing said interlocking valve, means for supplying said reciprocatory motor` with iiuid under pressure derived from said arc extinguishing blast, means admitting fluid under pressure from said conduit to said reciprocatory motor upon closing of said interlocking valve, and means under` the control of said interlocking valve for preventing said admission of fluid from said conduit to said reciprocatory motor as long as said interlocking valve remains in the open position thereof. Y

8. In a switching arrangement, the combination of relatively movable contact means for Aopening and closing an electric circuit, motor means operated by fluid under pressure for ac-y tuating said contact means, tripping means for initiating opening of said contact means by said motor means, a first conduit to be supplied with fluid under pressure upon operation of said tripping means, a valve, a second conduit controlled by said valve for supplying iiuid under pressure to said motor means for closing said contact means, a slide valve arranged in said second conduit and comprising a valve housing and a, valve element adapted to be moved selectively to an f open position and to a closed position, means in said housing dening a iirst port for admitting into said housing uid under pressure from said first conduit, means in said housing defining a second port for admitting into said housing fluid under pressure from said second conduit, and means in said housing dening a third port for interconnecting said housing and said motor means, said valve element comprising a pair of pistons slidable in saidfvalve housing and a stem l in series with a plurality of cooperating disconneet contacts, a rst motor means actuated by fluid under pressure for separating said arcing contacts, a second motor means actuated by fluid under pressure for engaging and disengaging said disconnect contacts, a source of iiuid under pressure, tripping means for initiating separation of said arcing contacts and of said disconnect contacts respectively by said rst and second motor means and for initiating establishment of an arc extinguishing blast of uid under pressure from said source adjacent said arcing contacts, a rst conduit to be supplied with fluid under pressure upon operation of said tripping means, a valve, a second conduit controlled by said valve for supplying iiuid under pressure to said second motor means for closing said disconnect contacts, a slide valve arranged in said second conduit and comprising a valve housing and a valve element adapted to be moved selectively to an open position and to a closed position, means in said housing defining a 'first port for admitting into said housing fluid under pressure from said iirst conduit, Vmeans in said housing defining a second port for admitting into said -housing fluid under pressure from said second conduit, and means in said housing deiining a third port for interconnecting said housing and saidsecond motor means, said Valve element comprising a pair of pistons slidable in said valve housing and a stem joining said pistons, one of said pistons being situated in the open position of said valve element between said first port and said second port, land in the closed position of said valve element between said second port and said third port, said third port being situated between said pistons in both positions of said Vvalve element.

1G. In a switching arrangement means ior interrupting a circuit including a source of fluid under pressure and pneumatic tripping means for initiating a circuit interruption causing now of fluid under pressure, circuit closing means including a pair of relatively movable contacts, a fluid operated motor for causing engagement of said lcontacts, a conduitor supplying fluid under .pressure from said source to said motor, a control valve arranged in said conduit, a piston type interlocking valve arranged in said conduit between said control valve and said motor and comprising a cylindrical valve housing deiining a passage forming an integral part oi said conduit, a valve element having axially aligned pistons slidable in said housing and joined by a stem portion enabling fluid to iio-iv through said conduit and said housing when said valve element is in open position, and biasing means acting upon said Valve element in a direction longitudinally thereof and tending to maintain said Valve element in open position, passage means for diverting to said interlocking valve a portion of said now of fluid under pressure, and means for causing said diverted portion of Said flow of fluid under pressure to act upon one of said pistons of said valve element to move said valve element in closing direction to admit nuid under pressure from said control valve to said one of said pistons of said valve element to cooperate with said diverted portion of said now ci iluid under pressure.

1l. n a switching arrangement, means for interrupting a circuit including a Source of uid under pressure and pneumatic tripping means for initiating la circuit interruption causing ow of iiuid under pressure from said source, closing means including a pair of relatively movable contacts, a duid operated motor ior causing engagement of Said contacts, a conduit for supplying fluid under pressure from said source to said motor, a control valve arranged in said conduit, a piston type interlocking valve in said conduit arranged between said Vcontrol valve and said motor and comprising a cylindrical valve housing dening a passage forming an integral part of said conduit, a valve element having axially 'aligned pistons slidable in said housingV and a stem portion joining said pistons forv enabling fluid to flow through said housing when said valve element is in the open position, and biasing means acting upon said valve element in a direction longitudinally thereof and tending to Ymaintain said valve element in open position, and means responsive to operation of said tripping means for moving said valve element in closing direction against the action of said biasing means to admit fluid under pressure from said control valve to an axially outer surface of said valve element to maintainrsaid valve Velement in closed position 13 by the action of iluid under pressure flowing through said control valve in the event oi said control valve being opened at the time said tripping means are operated.

12. In a switching arrangement, the combination of a plurality of cooperating contacts, motor means actuated by nuid under pressure for separating said contacts, a Source of fluid under pressure, tripping means for initiating separation of said contacts by said motor means and for initiating establishment of an arc extinguishing blast of fluid under pressure from said source adjacent said contacts, a valve, a lconduit controlled by said valve for supplying iiuid under pressure from said source to said motor means for closing said contacts, a dual purpose interlocking valve arranged in said conduit, means for biasing said interlocking valve to the open position thereof, a fluid operated reciprocatory motor for closing said interlocking valve, means for supplying said reciprocatory motor with fluid under pressure derived from said arc extinguishing blast, said interlocking valve admitting fluid under pressure from said conduit to said reciprocatory motor and venting said motor means to atmosphere upon closing of said interlocking valve, said interlocking valve preventing said admission o-f iiuid from said conduit to said reciproleatery motor as long as said interlocking valve remains in the open position thereof.

13. In a switching arrangement, the combination of a housing, an electric switch comprising relatively movable contact means for opening and closing a circuit, a motor operated by duid under pressure for actuating said contact means, a source of fluid under pressure, a conduit for supplying uid under pressure from said source to said fluid operated motor, a first valve for co-ntrolling the admission of iluid under pressure from said source to said conduit, a second valve arranged in said conduit between said nrst valve and said iluid operated motor, resilient means for biasing said second valve to the open position thereof, motor means for closing said second Valve against the action of said resilient means, means connecting said motor means with said source to cause 'closure of said second valve, means responsive to operation of said motor means for iconnecting said motor means with the section of said conduit situated between said first 14 and second valves for maintaining said second valve in closing position thereof, and linkage means causing closure of said second valve upon removal of said switch from said housing.

14. In a switching arrangement, the combination oi' a housing, an electric switch comprising a plurality of cooperating arcing contacts in series with a plurality of cooperating disconnect contacts, a first motor means actuated by fluid under pressure for separating said arcing contacts, a second motor means actuated by fluid under pressure for disengaging said disconnect contacts, a source of fluid under pressure, tripping means for initiating separation or" said arcing contacts and of said disconnect contacts by said first and second motor means respectively and for initiating establishment of an are extinguishing blast of iluid under pressure from said source adjacent said arcing contacts, a Valve, a conduit controlled by said valve for supplying uid under pressure from said source to said second motor means for closing said disconnect contacts, an interlocking valve arrange-:l in said conduit, means for biasing said interlocking valve to the open position thereof, a uid operated reciprocatory motor for closing said interlocking valve, means for supplying said reciprocatory motor with fluid under pressure derived from said arc extinguishingblasty said interlocking valve admitting fluid under pressure from said conduit to said reciprocatory motor upon closing of said interlocking Valve, said interlocking valve preventing said admission of fluid from said conduit to said reciprocatory motor as long as said interlocking valve remains in the open position thereof, and linkage means causing closure of said interlocking valve upon removal of said switch from said housing, said linkage means preventing engagement of said disconnect contacts until said switch is back in position in said housing.

JOHN F. CHIPMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,363,283 Baker et al Nov. 21, 1944 2,394,086 Ludwig et al. Feb. 5, 1946 

